Air heating device for incorporation in printing apparatus



June 14, 1960 A. M. HALLEY AIR HEATING DEVICE FOR INCORPORATION IN PRINTING APPARATUS Filed July 1, 1958 United States Patent Filed m 1; loss, Seiu'No. 745,882

Claims. Cl. 219-39 1;.

This invention relates to an improved air heating device for incorporation in printing apparatus and has for its object to provide a compact electrically heated source of hot air which may be mounted in close proximity to a printed web for directing a transverse series of jets of hot air onto the printed web.

The invention consists of a tubular air heating device for incorporation in printing apparatus comprising a tubular body, a longitudinal partition provided within said body to furnish a longitudinally extending plenum therein, and at least one longitudinally extending resistance element mounted in the plenum, the partition being provided with one or more longitudinally extending series of apertures to permit the uniform distribution of cold compressed air into the plenum from the tubular body part exterior of the plenum, and the tubular body being provided with a longitudinal series of apertures which are adapted to direct from the plenum hot air jets from the exterior of the said body.

Preferred means for carrying the present invention into practice will now be described with reference to the accompanying drawings wherein:

Figure 1 illustrates a part sectional perspective view of an air heating device according to the invention, and Figure 2 is a cross section on the line 22 of Figure 1.

As seen in the drawings the heating device comprises a relatively long cylindrical metal tube 3 which constitutes the body of the device and within this tube 3 a second tube 4 having the generally key-hole cross-section clearly seen in Figure 2 is mounted as a push fit. The ends of the second tube 4 are closed by a pair of end plates 5 which are adapted to permit the entry of compressed air into the space designated A which is defined between the walls of the body tube 3 and the second tube 4.

Within the second tube 4 is mounted as a push fit a third tube 6 having an inwardly curved circumferential part 6a in register with and serving to close the innermost end of the outwardly divergent section 4a of the tube 4 thereby to define an intermediate chamber B within the interior of the inner tube 6 and a plenum C in the divergent section 4a.

To permit the entry of air from the chamber A into the intermediate chamber B opposite sides of the tubes 4 and 6 are provided with registering apertures 4b and 6b respectively; and to permit the passage of air from the intermediate chamber B into the plenum C the wall portion 6a of the tube 6 is provided with a series of longitudinally elongated slots 6c extending over substantially the whole of the length of the tube 6.

It will be appreciated that the apertures 4b and 6b are spaced along the sides of the tubes 4 and 6 as necessary to provide a substantially constant air pressure distribution within the chamber B, the necessary spacing being determined by experiment.

Mounted inapertures 5a in the end plates 5 is at least one and desirably three electrical resistance elements 7 which when connected through leads 8 to a source of electricity are adapted to heat the compressed air passing of the device alternate slots in the tubes}, and4 are mise- 2,941,062 Patented June 14, 1960 through the plenum chamber C. The resistance elements are conveniently. of the. type wherein a helically wound resistance element is incorporated within and insulated from a cylindrical'rnetal sheath. c

' To permit the passage of the heated air from the plenum C to the exterior of the body 3' in the form of a longitudinallycontinuous hot air jet the arcuate end wallof the divergent tube section 4a and the wall of the body 3 are provided with a longitudinally extending series jofregistering elongated slots 40 and 3a respectively. 'To obtain an air jet 'extendinglover thtB'WhOiC of the length of the body aligned and arranged with overlapping ends'as shown in second tube are somewhat wider than the narrow slots 3a in the body to afford easy registration of these slots.

One or more of the heating devices above described can be provided in any convenient manner with one or both ends of each device coupled to a source of compressed air in such a manner as to permit the entry of the compressed air into the end or ends of the tubular bodies, each device being mounted so that the jets of hot air emerging from the slots 3a are directed onto and across a web of material being processed.

It will be appreciatedthat a heating device according to this invention is particularly economical in use since the hot air which is directed onto the web is heated in close proximity to the web whereby heat losses are reduced to a minimum. The heating device therefore has greater efficiency than the conventional arrangement wherein the air is heated at a remote point and is led to the printing apparatus by ducting.

I claim:

1. A tubular air heating device comprising a tubular body, a second tube having a generally key-hole section mounted within the body to define an outer air chamber between the walls of said tubes, a longitudinally extending partition dividing the second tube into an intermediate air chamber and a plenum, at least one electric resistance element longitudinally mounted in said plenum, the second tube, the partition and the tubular body each being provided with apertures to admit of the uniformly distributed passage of air from the outer air chamber into the intermediate chamber, from the intermediate chamber to the plenum, and from the plenum to the exterior of the body in the form of a hot air jet extending across substantially the whole of the length of the body of the device.

2. A tubular air heating device comprising a tubular body, a second tube mounted within the body to define an outer air chamber between the walls of said tubes, a longitudinally extending partition dividing the second tube into an intermediate air chamber and a plenum, at least one electric resistance element longitudinally mounted in said plenum, the second tube, the partition and the tubular body each being provided with apertures to admit of the uniformly distributed passage of air from the outer air chamber into the intermediate chamber, from the intermediate chamber to the plenum, and from the plenum to the exterior of the body in the form of a hot air jet extending across substantially the whole of the length of .the body of the device.

3. A tubular air heating device according to claim 2, wherein the said partition is formed by a third tube mounted within the enlarged sect-ion of the second tube.

4. A tubular air heating device according to claim 2,

wherein the apertures in the tubular body take the form 5. A tubular air heating device comprising a hollow tubular body, tubular partition means extending, longi:

tudinally within said body, said partition means extending transversely entirely across the interior of said body longitudinally extending; intermediate-chamber and a .l'ongitudinally extending. plenumthatlie mainlyon opposite:

sides'of the longitudinal axis Qf-the body, means closingthe:opposite ends of said plenum andJintermediate cham-v ber, said intermediate chamber having a longitudinal series of side openings connecting said internal air chamberswith saidintermediate chamber and a longitudinal. I series-ofopenings in saidiinternal wall. connecting the: in- 15 1,0 2,7

, termediateehamber withsaidplenum heater means extendingalong said plenum, and means providing a 1011- gitudinal series of hot air discharge openings from said plenum through said body.

References Citedginzthejle of this patent UNIIED; STATES; EAT-ENTS FOREIGN BATENTSZ France: .V Sept. 30, 1953 

